The present invention relates generally to fiber optic cables.
Fiber optic cables include optical fibers that are capable of transmitting voice, video, and data signals. Fiber optic cables have advantages over electrical voice, video and data signal carriers, for example, increased data capacity. As businesses and households demand increased data capacity, fiber optic cables can eventually displace electrical voice, video, and data signal carriers. This demand will require low fiber count optical cables to be routed to end users, for example, businesses and households.
Fiber optic cables can typically be used in various applications. For example, fiber optic cables may be suitable for both aerial and buried cable applications. More specifically, a fiber optic cable may be strung between poles and/or buried in the ground before reaching the end user. Aerial and buried cable environments have unique requirements and considerations. Optical fiber cables should meet the unique requirements and considerations of intended environments, yet still remain cost effective.
In addition to being cost effective, cables should be simple to manufacture. An example of a low fiber count optical cable manufactured in one step and having optical fibers disposed longitudinally to the cable axis is disclosed in U.S. Pat. No. 5,115,485. An optical fiber is disposed within an electrically conductive strength member that is surrounded and embedded in an elastomeric material that forms the outer jacket. The cable also includes optical fibers embedded in the elastomeric material. This known fiber optic cable has several disadvantages. For example, because the electrically conductive strength member surrounds the optical fiber, it is difficult to access the fiber. Moreover, accessing the central optical fiber may result in damage to the embedded optical fibers. Additionally, the embedded optical fibers are coupled to the elastomeric material that forms the outer jacket. Consequently, when the elastomeric outer jacket is stressed, for example, during bending, tensile and compressive stresses can be transferred to the optical fibers, thereby degrading optical performance.
Moreover, fiber optic cables that are strung between poles can carry a tensile load. An example of a fiber optic cable designed to carry a tensile load is disclosed in U.S. Pat. No. 4,166,670, which is incorporated herein by reference. This known optical fiber cable requires a plurality of stranded strength members having circular cross-sections. The stranded strength members define tricuspid interstices therebetween in which an optical fiber is disposed. During manufacture, the interstices can be filled with petroleum jelly while the circular strength members and optical fiber are stranded together. Although this known fiber optic cable is designed to prevent the application of tensile stress to the optical fibers, this design has several disadvantages. For example, costs are higher because the helical orientation of the optical fibers necessitates the use of a longer length of optical fiber than the length of the cable in which it resides. Moreover, from a manufacturing standpoint, it can be more difficult and expensive to strand the strength members and optical fibers.
One aspect of the present invention provides a fiber optic cable having at least one interface being formed by a plurality of adjacent support members. Adjacent the interface is at least one retention area having an optical fiber component disposed therein. The retention area is disposed generally longitudinally and non-helically relative to an axis of the cable. The cable also includes a cable jacket substantially surrounding the support members. The cable can include a cushioning zone adjacent the optical fiber component, a water-blocking component and/or an interfacial layer at least partially disposed between an outer surface of the support members and the cable jacket.
Another aspect of the present invention provides a fiber optic cable having at least one interface being formed by a plurality of adjacent support members. Adjacent the interface is at least one retention area having an optical fiber component disposed therein. The retention area is disposed generally longitudinally and non-helically relative to an axis of the cable. The cable also includes a cushioning zone and both an interfacial layer and a water-blocking component at least partially disposed between an outer surface of the support members and a cable jacket generally surrounding the support members.
A further aspect of the present invention provides a fiber optic cable having at least one interface being formed by a plurality of adjacent support members. Adjacent the interface is at least one retention area having an optical fiber component disposed therein. The retention area is disposed generally longitudinally and non-helically relative to an axis of the cable, the cable preferably having a strain of about 1.0% or less when a 1,000 lb. tensile force is applied. The cable can include a cable jacket, a cushioning zone, a water-blocking component and/or an interfacial layer.